Water: Purification Methods

Things you should know before you try to purify a water source.

When Lewis and Clark explored the nation’s vast interior in the early 1800s, they actually obtained some of their drinking water directly from the Missouri River. Amazingly, they didn’t do anything to purify it, other than probably leave it sit in barrels so that the silt would drift to the bottom. Today, of course, if you did that, you’d become extremely ill; after a hard rain, the river is filled with all sorts of pollution, including poorly treated sewage overflow from waste water treatment plants. The upshot, for preppers, is that you have to get used to the idea that we no longer live in a pristine world, and even if civilization collapses, it’s not going to revert immediately to its unspoiled state. Thus, whether you resupply from a stream or from rainwater, it’s not safe to drink that water without treating it to remove harmful substances and pathogens that can make you extremely ill.

Fortunately, according to Practical Preppers’ Scott Hunt, water purification is something that preppers can easily accomplish, thanks to a multitude of technologies that are available, ranging from the old standby of boiling water, to ceramic filters and ultraviolet light. As prepper author James Wesley Rawles notes, various purification methods may remove one sort of contaminant or pathogen, but let others slip through. Treating water with chlorine will kill bacteria, but not all viruses, for example, and no filter system is 100 percent effective at removing herbicides and pesticides that may contaminate an open body of water. So if you filter water, you’d be smart to use distillation, ultraviolet sterilization, and/or chemicals as an additional precaution. One how-to manual that gives a detailed rundown on pathogens, contaminants and various methods of water purification is the Handbook to Practical Disaster Preparedness for the Family, by Arthur T. Bradley and several co-authors.

Here are some tips on how to make sure that the water you collect is fit for drinking and other uses.

Know Your Water. Hunt recommends testing the water source in advance to determine what sort of microorganisms or contaminants it might contain, so that a prepper can have the right filters to deal with each problem.

Master the Easy, Basic Techniques for Killing Bacteria. Boiling is one of the safest and most effective methods of treating water, according to the Federal Emergency Management Agency. In a large pot or kettle, bring water to a boil—you’ll notice the bubbling and steam streaming out out the vessel—and keep it there for one minute. (Keep in mind that some of your supply will evaporate, so don’t let it boil too long.) Then let the water cool to a temperature that’s comfortable for drinking. Boiled water will taste better if you re-oxygenate it by pouring the water back and forth between two clean containers. Another way to kill loathsome critters in your water is to treat it with bleach. Use a regular, unscented variety that contains 5.25 to 6 percent sodium hypochlorite, and buy a lot of small bottles, because bleach’s potency diminishes after it’s opened. To treat water, add 16 drops (1/8 of a teaspoon) to a gallon of water, stir and let stand for 30 minutes. Hunt notes that ceramic filters provide good protection against bacteria, and they don’t require any energy expenditure—just gravity. “You just dump the water in the top, and it filters down,” Hunt explains. “The bacteria can’t get through the top."

Use Distillation to Get Rid of Really Nasty Stuff. Distilling water will remove microorganisms that somehow survive bleach, boiling, and other methods. In addition, it will remove heavy metals, salts, and other chemical pollutants that can harm your health. Basically, the process involves boiling water so that it leaves behind all the stuff that has contaminated it, and then collecting the vapor and allowing it to condense back into liquid water. You can create a simple distilling apparatus simply by suspending a cup by attaching it to the inside of a large pot’s lid, and then putting a layer of water in the bottom of pot and boiling it for 20 minutes. As the pot cools afterward, the water that drips down into the cup is purified. If you’re concerned about using up fuel, it’s also possible to build a solar energy-powered distiller. Here are some simple instructions on that from a prepper blogger.

Get an Ultraviolet Light. Large water treatment facilities have used ultraviolet radiation to kill pathogens for years, but small portable units for use in the home or out in the wild have only recently become available. Basically, an ultraviolet purifying unit is a bottle with a small light source that’s inserted into the water. After 30 to 80 seconds, the radiation kills most microbes. Ultraviolet treatment won’t remove impurities such as dirt, metals or chemicals from the water, however, so you’ll have to combine it with another method to get really clean water.

If You Only Do Three Things:

Get a Basic Ceramic Filter. This is the lazy man’s way to get rid of bacteria, but Hunt says it’s pretty effective.

Stock Up on Bleach. It’s great for killing microorganisms that can may you really sick.

Boiling Water is a Really Easy, Quick Method of Purification. You can bring a pot or kettle of water to a boil and keep it rolling for a minute, let it cool, and you’re pretty safe from bacteria.

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